Cob on & Piffy on a rock cake

: I frequently use the expressions "to have a cob on" when someone is in a bad/cantankerous mood and "sitting like Piffy on a rock cake" when someone has left you hanging around waiting for something/one that is not going to appear/happen.

: Does anyone have any idea where these phrases originate?

To access previous discussions about "piffy," search under same in the archives.

Regarding cob. I've heard (in W.Va.) someone talk about another person having a cob up his a**. I'm not sure how that could happen but it makes people grouchy.